In coronary angioplasty and related technologies, a catheter having an inflatable balloon attached at the catheter's distal end is employed. Such balloons have been known to fail by damage resulting from abrasion and puncture during handling and use and also from over-inflation. Additionally, the balloons and catheters upon which they are mounted generally have a higher coefficient of friction than desired for ease of use. Thus, it often becomes difficult to guide the catheter into a desired location in a patient due to friction between the apparatus and the vessel through which the apparatus passes.
A variety of urethane based coating compositions for medical applications are known in the art. For example, U.S. Pat. No. 4,642,267 to Creasy et al. describes hydrophilic polymer blends useful for coating catheters and other surfaces. The coating comprises a thermoplastic polyurethane and a hydrophilic poly (N-vinyl lactam) such as polyvinylpyrrolidone. Additional components such as crosslinking agents and wax dispersions can be added to the blend. U.S Pat. No. 4,675,361 to Ward, Jr. relates to polymer systems useful for coating surfaces having blood and tissue contacting applications. The system ccmprises a base polymer, such as a polyurethane, containing at least one polymer additive comprising a segmented block copolymer having both hard and soft segments.
Although each of these patents describes an application involving biomedical apparatus, a need still exists for a simple, easy-to apply coating which is biocompatible, lubricious and provides a protective layer to the surface upon which it is applied.